The goal of the proposed research is to understand the behavioral and physiological functioning of the chemical senses, with an emphasis on taste. To approach an understanding of gustation we are using a mammalian species, the laboratory mouse (Mus domesticus, nee Mus musculus domesticus), that is amenable to behavioral genetic and physiological experimentation. The overall plan involves three phases. In the first a screening procedure was employed to identify inbred strains of mice that are genetically aberrant in response to specific chemical stimuli. Further psychophysical and sensory electrophysiological techniques were applied to validate screening results. In the present second phase methods of behavior genetics are applied to identify the precise nature of the genetic involvement in extreme tasting phenotypes, and to develop special genetic stocks for rigorous investigation of taste mechanisms. In the third phase the genetic stocks which result from this second phase are to be used to analyze mechanisms of taste at levels from the biochemical to the behavioral. The primary health relatedness of this research is that taste allows monitoring of food taken into the oral cavity and detects and discriminates the many chemical compounds of this food. Taste factors and related dietary concerns are of central relevance to health in a wide variety of matters ranging from obesity to cachexia.